Automated portable friction welding system and method of operation

This application is a national phase entry under 35 USC 371 of International Patent Application No.: PCT/US2020/019483 filed 24 Feb. 2020.

This application claims the benefits of the filing date of provisional application Ser. No. 62/809,825, filed by Fix et al on Feb. 25, 2019 for An Improved Automated Portable Friction Welding System and Method of Operation, the full disclosure of which is hereby incorporated by reference.

The present invention relates to a system, method and components for joining a workpiece to a substrate, and more particularly, to a portable friction welding system, its components, method of operation and application.

The present invention supports installation, fabrication and repair operations relying on the installation of fastening elements to a substrate. Such fastening elements (also called workpieces, fittings or fixtures) include, for example, externally threaded studs, internally threaded bosses, bolts and other fittings for which installation operations have been dominated by conventional mechanical means, legacy/conventional welding techniques and explosive/electrical discharge means. For instance, some methods for attaching fastening components involve placing bolts through drilled holes. Others place a stud in a tapped hole. Still other methods include legacy welding in an attempt to form a strong, cohesive, high strength, fine grain weld bond. Typically, this might be attempted through arc welding, oxyfuel gas welding, flash welding, brazing, soldering, electron beam welding, or laser beam welding techniques.

However, drilling and tapping takes time, and in many cases, it is not possible to drill through a substrate. Aligning pre-drilled holes may cause problems. In many common welding applications, the exposed flame, arc or electrical discharge creates a hazard/ignition and may not be practical to use. For example, in areas where combustible gases are present, it is not usually possible to use an open flame or arc welding procedure due to the inherent danger of fire or explosion. Further, the heat generated through such processes may lead to a loss of structural integrity in the bond or adjacent material and may compromise coatings and liners on both the face and back side of the substrate. And material compatibility is another area of concern, e.g., in materials that are difficult themselves or in material combinations that are problematic. Examples include challenges welding in stainless steel or aluminum, stainless steel to aluminum or in combinations of stainless steel to carbon steel. While some of these can be tackled on occasion by those of highly specialized skill, much of this remains a difficult area frequently subject to inconsistent and unsatisfactory results at the hands of the common skill levels that are readily available in the generally welding trade applying other tools and methods.

There have been limited attempts to address the need for a versatile tool that can provide efficient, consistent, high quality welds with portable friction welding systems. Broadly, friction welding is a process for joining materials using a combination of pressure and movement at the interface of a workpiece to be joined and a substrate. Friction induces very localized heating from rotating a workpiece held against a substrate to which it is being joined. After the material at this intersection has plasticized, rotation stops and forging pressure holds the workpiece against the substrate until the localized plasticized material fully solidifies and the weld is complete. However, the success of these tools has been limited by excessive reliance on highly specialized skilled labor. Further improvements in automating the use of portable friction welding systems have been required to extend the ability to provide efficient, consistent, high quality welds with portable friction welding systems to tradesmen requiring less, more modest specialized training over that which defines ordinary skill in the welding arts.

And more specific examples can greatly benefit from practice of the present invention. A particularly advantageous application of the present technology is to weld aluminum or stainless steel to aluminum substrates. Ship building and other maritime and offshore applications value the benefits of aluminum in resisting corrosion. And while some electrical discharge welding techniques have been developed that can work in a dry environment, they are not suitable for underwater application. Thus, even as more and more ferries, patrol boats, naval and maritime vessels are using aluminum hulls, the ability to weld underwater with workpieces and substrates in aluminum alloys such as the 5000 or 6000 series or with stainless steel workpieces such as the 300 series to aluminum substrates has remained a daunting a challenge, one understood in the industry to severely limit the feasibility of conducting installation and repair procedures in the field below the waterline.

Therefore, there remains a substantial need for an improved portable welding system, tool and method to more broadly and successfully bring the benefits of portable friction welding to industry.

To achieve these and other advantages in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention relates, in part, to an automated portable friction welding system for friction welding a workpiece onto a substrate. This system comprises a power system selected from one or more of a group comprising pneumatic power, hydraulic power and electrical power and operably connects the power system to a portable friction welding tool which comprises a tool housing having a longitudinal axis, an actuator received in an axially slidable relation within the tool housing and a rotary motor disposed in the tool housing and engaged to said actuator to slide therewith. Further, the system comprises a collet configured to receive the workpiece and a transmission or drive train within the tool housing connecting the motor to the collet. Other aspects of this claimed embodiment comprise a start input and an automated control system which comprises a motor control system operably connected and to a power source and responsive to a signal from the start input to cause the motor to spin the workpiece, a first axial thrust control system operably connected to the start input and disposed to begin a first input to the thrust building cycle acting upon the actuator upon receipt of the signal from the start input, an upset phase control system responsive to axially sliding of the actuator whereby the end of the desired actuator stroke operates to cut the motor off and to initiate and then hold a second potential input to the axial thrust cycle acting on the actuator and therethrough to the interface of the workpiece and substrate. And a reset input is operable to release the thrust in the actuator at the end of a cool down phase.

Another feature of some embodiments of the present invention is a versatile, automated friction welding tool for receiving power from a power source and friction welding a potential range of workpieces onto any of a range of potential substrates. The tool comprises a tool housing having a longitudinal axis; an actuator axially slidably received within the tool housing; a rotary motor disposed in the tool housing and engaged to said actuator to slide therewith; a collet configured to receive the workpiece; and a transmission or drive train within the tool housing connecting the motor to the collet. The tool further comprises a start input; an automated control system comprising a motor control system operably connected to the power source and responsive to a signal from the start input cause the motor to spin the workpiece; a first input to the axial thrust control system operably connected to the power source and the start input and disposed to begin a an adjustable first thrust building cycle acting upon the actuator upon receipt of the signal from the start input; an upset phase control system responsive to axially sliding of the actuator whereby the end of the desired actuator stroke operates to cut the motor off and to potentially initiate the contribution of a second input to the axial thrust cycle acting on the actuator and to hold the thrust or forging force therethrough acting at the interface of the workpiece and substrate; and a reset input operable to release the thrust in the actuator at the end of a cool down phase.

A further feature of the present invention addresses a method for automating a versatile friction welding process for friction welding a variety of workpiece/substrate combinations using a portable friction welding system. A workpiece is installed into a collet of a portable friction welding tool and the workpiece is positioned at the weld site and a tool housing of the portable friction welding tool is secured to the substrate. An automated friction weld cycle is initiated beginning with a burn off phase, comprising engaging a rotary drive to rapidly spin the workpiece about a longitudinal axis and engaging a first component of the thrust cycle which progressively builds axial force driving the workpiece against the substrate at the weld site. This rapid spinning and axial thrust of the workpiece against the substrate combine to frictionally heat a localized segment of the weld site. An upset phase is initiated in the automated friction weld cycle, comprising plasticizing localized heated material at the weld site and axially translating the workpiece into the substrate at the weld site. The upset phase transition to a cool down phase uses a control instruction responsive to an adjustable amount of axial translation of the workpiece to disengage the rotary drive to stop spinning the workpiece about its longitudinal axis and uses the control instruction to potentially engage a second component of the axial thrust component acting on the workpiece to advance the workpiece to a final weld position and maintain force pressing the workpiece into the substrate at the weld site for the cool down phase. No second component is provided if the first thrust component has achieved full levels. After the cool down phase, the workpiece is released from the collet which is withdrawn away from the substrate. The portable friction welding tool is then available for repeating operations at other locations on the substrate, if desired.

Yet other embodiments for practicing a portable friction welding operation addresses a method for welding an aluminum workpiece to an aluminum substrate in an underwater environment. A workpiece is installed into a collet of the portable friction welding tool and a housing of the portable friction welding tool is clamped to the substrate. A burn-off phase is initiated comprising engaging a rotary drive to rapidly spin the aluminum workpiece about a longitudinal axis and engaging a first component of the thrust cycle which progressively builds axial force driving the aluminum workpiece against the aluminum substrate at the weld site. The rapid spinning and axial thrust of the aluminum workpiece against the aluminum substrate combine to frictionally heat a localized segment of the weld site in a burn-off phase. An upset phase is initiated in the automated friction weld cycle, comprising plasticizing localized heated material at the weld site and axially translating the workpiece into the substrate at the weld site. The rotary drive is disengaged to stop spinning the aluminum workpiece about its longitudinal axis and a cool down phase is initiated whereby the weld is allowed to fully solidify while holding thrust across the weld and allowing the weld to fully solidify. After cool down, the workpiece is released from the collet which is withdrawn away from the substrate and the clamp releases the portable friction welding tool from engagement with the substrate.

Additional features and advantages of the present invention will be set forth, in part, in the description that follows and, in part, will be apparent upon study of the description or can be learned by practice of the invention. The features and other advantages of the present invention will be realized by means of the elements and combinations particularly pointed out in the description and in the claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide a further explanation of the present invention, as claimed.

It is to be understood that the apparatus and methods described herein may be implemented in various forms and those skilled at the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention as defined by the patent claims. The detailed description describes several distinct embodiments and it will be understood that not all of that detail, while exemplary, is essential to the claimed invention. Thus, other modifications, changes and substitutions are intended to the foregoing disclosure and, in some instances, some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate for the patent claims be construed broadly and in a manner consistent with the spirit and scope of the invention herein.

Friction welding processes have been in use in factory settings for decades in extremely large, heavy bed lathe machines. More recently, portable friction welding devices have been developed to allow friction welding deployment in the field.provides a rough timeline for welding with a portable friction welding system. This timeline correlates the friction welding stage with what is happening in the motor, the forging piston and in the materials to be joined, respectively. Friction welding has three stages, a burn off phaseA, and upset phaseB and a fusion or cool down phaseC. In the burn off phase, the motor provides rotationto the workpiece and, in pneumatic and hydraulic systems, pressureA builds in the forge piston to provide thrust forcing the rotating workpiece against the substrate such that the friction produces substantial localized heat at the intersection of the workpiece and the substrate, see stageA for the material. Rotationin the motor continues in upset phaseC and further force in the forging piston begins to cause advancementB of the workpiece into the substrate as the materials at the intersection plasticize, see stepB for the material. In an embodiment of the automatic portable friction welding of the present invention, advancement of the forging pistonB turns off rotationfrom the motor and creates the potential for a thrust boostD in the forging piston, if needed, as the friction welding process enters cool down phaseC and the weld material joining the workpiece and the substrate solidifiesC. Forging pressureC is maintained throughout the cool down phaseC. The automated cycle typically takes two to four seconds and ceases when the motor cuts off, rotationceases and the second stage thrustC has been applied, if any. A manual wait time on the order of twenty to thirty seconds in most circumstances completes the cool down phaseC and weld solidificationC and the thrust can be released and the tool removed from the installed workpiece.

is a schematic representation of major components of one embodiment of a portable friction welding systemfor bonding a first element, fixture or workpiece(most often in the form of an externally threaded stud or an internally threaded boss) to a substrate. In this illustrative embodiment, system, the power source is a pneumatic system in which an air supply is provided by a compressorhaving a regulatorA and is connected to a supply manifold. The supply manifold has air quality provisionsA to filter and remove moisture. Air pressure from the supply manifold is conducted to portable friction welding toolthrough an air supply lineA. In this embodiment of tool, the actuator is in the form of a forging pistonand the air supply provides both a forging pressure and translation of the actuator and drives a motorto import rotary motion to first elementthrough a colletbefore exhausting through exhaust lineB. In applications where portable friction welding toolis deployed underwater, components of air supplywill typically be provided as topside equipment and connected to toolthrough a bundled umbilical of air supply lineA, exhaust lineB and, if the clamp calls for it, vacuum lineC. Bringing the exhaust to the surface allows a single pressure system and mitigates the chance of water intrusion into the portable friction welding tool. This provides for a more dependable tool and mitigates maintenance requirements. Underwater applications will also be facilitated by adding buoyancy provisions to the portable friction welding tool to make for easier diver handling and to render the umbilical of bundled flowlines substantially neutrally buoyant.

Clampfacilitates holding forging pressure and resisting torque at the interface of workpieceand substrateduring the friction welding process. Clampmay be in any form, including, but not limited to, a mechanical connection such as a “c” clamp or a chain clamp or, as provided here, a vacuum clamp which is connected to a vacuum feed off compressorthrough vacuum controlsC of supply manifoldthrough vacuum lineC.

Effective and automated control over the friction welding operation is an important feature of the portable friction welding tool. For the purposes of clarity, control features were omitted from the schematic of mechanical elements in. However, these aspects are introduced in connection with the functional map of.

Referring to, the “remote” power sourcemay be pneumatic, hydraulic or electrical in nature (or a combination thereof) to drive a motor systemand an actuator. For this illustrative example, the power supplyis an air compressorhaving a pressure regulatorA, titterA, and a manifoldC presenting air supplyB. The air supply interacts with drive and automatic control systemsB that serves motor systemC (here an air motor) and control and drives systems for an actuator, here forging piston system, through controlling driversD andG, Motor systemincluding air motorA and motor control provisionsB, impart rotation of workpiece(See). An operator pushing start buttonD instructs motor control assemblyto turn air motorA on and instructs thrust controlD to begin building forging pressure acting on forging pistonA to produce thrust and then advance forging pistonA. Automatic shutdownis triggered by translation of forging pistonA which causes a signal for secondary thrust inputG and motor shut offC. An enhanced secondary thrust component is available if necessary, through controlsG. This contribution of secondary thrust can be mild or even non-existent if the full forging force required from the forging piston has already been reached through initial thrust controlD. And this forging pressure is held, stepH, throughout the cooldown period. This secondary input contribution can be mild or even non-existent if the full required pressure on the forging piston has already built through initial thrust controlD. Thus, the actuator/forging piston systemacts upon air motor system, and therethrough (see) to colletand to workpieceas it engages substrateduring friction welding, applying a controlled amount of thrust, over a proscribed time, to accomplish the bonding.

Function mapC also includes the function of positioning and securing tool housingA of the portable friction welding tool to substratewith clamp systemA. In this embodiment, clamp systemA is a vacuum system driven through a vacuum lineC from manifoldC.

The hardware of an illustrative embodiment of the present invention is addressed in.present elevational views of an illustrative embodiment of portable friction welding tool. It will be appreciated that the tool may be used in many orientations, e.g. to attach members from beneath a horizontal substrate surface (such as for repair to the bottom of a ship's hull), from beside a vertically oriented substrate surface (such as to mount equipment or repair a vertical wall of a tank or vessel), or from over a substrate surface (such as installation onto a deck or a repair to the top of a tank). However for the purpose of clarity, orientation of the tool will be described herein with the portable friction welding tool with its longitudinal axis of main housingand front housingin a horizontal position and with the “forward” end presenting colletand the “back end” presenting a housing end plate, an air supply inlet, exhaust nozzle, and operator controls. From this orientation,are views of the top, front, back, bottom, right side (viewed from the operator's perspective, behind the tool) and the left side, respectively, of these same components.

are perspective views illustrating the embodiment offrom the front/top/left side, back/top and front/top respectively. More detail of the constituent hardware components, both exterior and interior, are addressed in the “exploded” view of the principal hardware components of the embodiment of portable friction welding toolin. These components are for the same embodiment illustrated in, above. This exploded view is taken in the perspective, looking from the top/right/rear or operator side.

Again, the housing of the tool in this embodiment is made up of front housingwhich is bolted to main housingwith bolts(see) and sealed with housing end platesecured by bolts(see). An orificeA in main housingreceives the air supply inlet(see) to bring supply air into main housingand to fluid communication with air motor systemA and forging piston system, see. Further, orificeA of main housingis in fluid communication with the exhaust of the pneumatic circuit (discussed below) and receives exhaust nozzle. It may be convenient to make secondary filter provision in air supply inletor air supply nozzle.

OrificesC,D andE at the rear of main housingaccept the operator controlsfor reset, start and stop operations, respectively. These may be, e.g., poppet or spool valves, and include reset valve assemblyA, start valve assemblyB and stop valve assemblyC, which present reset buttonB, start buttonE and stop buttonH, respectively, for operator access. See also. These are also discussed in greater detail in connection with.

Returning to, movement of the actuator (illustrated here as a forging piston) managed by a forging pressure controller (“FPC”) modulefor building initial pressure and advancement. The FPC module comprises FPC module sleeveE and FPC valve stemF are received in orificeF through housing end plateand presents a dial in control for a given range of applications facilitating the versatility of this embodiment of the present invention. See also the cross-section of.

In this embodiment, the upset phase control system which is responsive to axial translation of the actuator (here forging pistonA) is provided by a forging area controller module (“FAC”). The FAC provides another dial in control supporting the versatility of the present invention to a wide range of materials and applications. In this embodiment, FAC modulecomprises FA controller elementA, FAC threaded insertB, FAC tipF and FA control knobC. Here, FAC module is received into the housing through orificeG through front housing, see. See also the detailed discussion of, below.

Returning to, the rear facing surface of main housingpresents three more orifices where internal control elements are received into tool housingA through main housing, orificesH,J andK, receiving a shut off sequencer or SVUCCV module, a V90 control system module, and a BKCV control system, respectively. End caps may help protect these components. See also. The forge pressure controller (“FPC”) moduleis received in orificeF. In addition, the forward face of main housingpresents an optional orificeN which can receive a pressure relieve valveand an optional access port at orificeM on the top of the housing receiving access cap. See.

Building from the rear, forward, inside housingA, supply valve pistonresides just forward of end platewithin press fit sleevewhich is received at the rear of the forging piston). Ahead of that, forging pistonA houses air motorA in a thrust bearing relation through air motor shims. And various o-ringsare illustrated to seal pistons within cylinders and across engaging surfaces of tool housingA and components installed through the housing to prevent the loss of air pressure, water intrusion and to define fluid passageways.

The output of air motorA is connected to colletthrough AM coupling nut, shaft couplerand shaft. This assembly passes through air motor seal spacerand, optionally, double seal x-profile o-ringsto seal air motorA from the drive components which are surrounded by internal bearing housingwhich engages the forward face of the air motor housingB. Press fit sleeveengages internal bearing housingand captures Bellville washersbetween sleeveand shoulders of internal bearing housing.

illustrate the push button operator controls of an illustrative embodiment in greater detail, illustrating the ends of operator buttonsand longitudinal cross-sections through the respective poppet valves, showing plungersJ connected to the respective buttons, poppet valve componentsK, biasing springsL, and sleevesM with portsP and sealsQ.

illustrate longitudinal cross-sectional views through portable friction welding tooltaken planes denoted as reference lines in front elevational view,and back elevational view. These cross-sectional views also illustrate the many boringsL into housingA through which precision drilling techniques are used to establish flow paths between relevant control and drive components in conducting air from air inlet, through supply nozzle, through these components and ultimately out exhaust nozzle. Straight line borings are brought in from different angles to intersect and establish fluid flow communication after which unused portion of the borings can be sealed, e.g., plugged or filled with epoxy. Other borings may be sealed with a tapped cap to leave access for instrumentation for tool diagnosis and/or calibration to for use in unfamiliar materials. Compare alsoL on the exterior of housingA, e.g.,and.

is a horizontal cross-section bisecting portable friction welding tooland FPC modulealong the longitudinal axis as shown in linesA-A in.is a partial vertical cross-section bisecting option purge or pressure relief valve, start valve assembleD and stop valve assemblyG as taken along the longitudinal axis and illustrated as lineB-B in.is a partial longitudinal cross-section taken to bisect each of SVUCCV, V90 vacuum moduleand BKCV.is a partial vertical cross-section bisecting reset valve assembly taken along the longitudinal axis and illustrated as lineD-D in. Andis a partial vertical cross-section bisecting taken along the longitudinal axis and illustrated as lineE-E inbisecting FAC modulewithbeing a closeup elevational view of that component. These figures will be discussed together in describing the broad mechanical operation of the portable friction welding tool and for the control system, refer toaddressing operation of the tool.

Air supply orificeA (see) passes supply air to the interior of housingA which, in this embodiment, comprises an assembly of main housing, front housingand housing end plate. Air motor assemblyA is received within forging pistonA, which is sliding received within main housing. Turning to, the forging piston can then provide thrust and displacement to air motor assemblyA and through shaft coupler, shaftand colletand supported by air motor seal spacer. This thrust is transferred to a workpieceto be joined such as a stud or boss mounted in the collet to press against the substrate while air motorA rotates such workpiece. (See.) This thrust imparted from actuator, here forging piston systemovercomes the rearward bias from the spring action of Bellville washer stackto push internal bearing housingforward. Spent air exits portable friction welding toolthrough exhaust nozzle. The position of various control elements is also illustrated in these cross-sections. For instance, supply valve pistonis illustrated inside the housing covered by housing end plate.

show the operator controls of this embodiment in greater detail, illustrating the ends of operator buttonsand longitudinal cross-sections through the respective poppet valves, showing plungersJ connected to the respective buttons, poppet valve componentsK, biasing springsL, and sleevesM with portsP and sealsQ. Refer to the broader context about these components in.

Similarly, the cross-section of, the closeup cross-section ofandlongitudinally bisect FAC moduleto illustrate FA controller elementA, FAC threaded insertB, FAC seatD and FA control knobC. Exterior threads on FAC threaded insertB securely receive the FAC module into orificeG through front housing. Threads internal to FAC threaded insertB then adjustably receive FA controllerA such that turning FA control knob or adjustment knobC will advance or withdraw FAC tipF of FA controller elementA and FAC seatD presented at the leading edge of forging pistonA. FAC tipF engages FAC seatD on the advancing forging piston, the engagement shuts off motorA and provides a secondary thrust through the forging piston to conclude the upset phaseB and to hold through the cool down phaseC of the friction welding process as introduced in. An appropriate setting for FAC moduleinteracts with the FPC setting and is a function of the materials and the application involved in the joint. Once “dialed in” the FAC module can be locked down with head capE through the welding operations appropriate to that setting for that job as discussed further in connection with.

In the illustrated embodiment, FACis aligned with the longitudinal axis of the portable friction welding tool. This facilitates a more sure, direct, and accurate controlled mechanical engagement with the leading edge of forging pistonA or the terminal end of an FAC receiving orificeP (see) which is advancing directly into the direction of the FAC alignment.

is an alternate embodiment of FAC moduleA. Here threaded insertB is formed integrally with FA controller elementA to present a FA controller elementof fixed length. There is no need for head capE. The knobB is not used for adjustment, but to screw FAC module all the way into orificeG to present FAC tip at a known, fixed position. Versatility is provided by having multiple FAC modules available, each of a unique fixed length and each configured for a specific application. Color coding can facilitate deploying the right module for the right application.

illustrate perspective views of alternate embodiments of forging pistonA. FIG. BA shows the forge piston ofin a larger illustration. Here circumferential grovesreceive square profile seal elementsto establish an effective seal between the sides of forging pistonA and the cylinder in which it moves.illustrates an alternate embodiment of a forging pistonA in which the forging piston has fewer groovesand the seal elements are round profile o-ringsA.

illustrates a forging pistonA having an indexing keywhich engages an axially disposed orifice in internal bearing housingand an indexing keywhich engages an axially disposed orifice in internal bearing housingand passes therethrough into an axially disposed orifice in front housing. These keys engage these orifices to prevent rotation of forging pistonA within its cylinder in response to a torque load from motor, the air motorA itself being mounted inside forging pistonA in a manner that resists rotation between air motorA and the receiving forging piston, e.g., by another axially disposed key extending from the back face of motorand into the rear face of the bore in main housing. Installation of forging pistonA into the cylinder of the boreF within main housingcan prove a difficult operation given the precision of alignment required, the long stroke of the insertion, and force required for this insertion given the tight tolerances of the tool. However, in the embodiment of, the sides of forging pistonA are relieved in regionL, providing tight tolerances where required, but a less tight fit elsewhere to facilitate assembly. Further, this embodiment illustrates an orificeP disposed to receive FAC seatD.

is a back elevational view of a portable friction welding toolof the embodiment ofin an underwater application attached to a clamp systemA, here illustrated as an embodiment with a vacuum clamping system.as a side elevational view of the portable friction welding tooland attached vacuum clamp illustrated intaken from the vantage point of lineB-B in. Use of a clamping system(see also schematic of) facilitates friction welding operations by connecting tool housingA directly to substrateto hold against reactive forces such that full effect of thrust and rotation is effectively concentrated at the interface of rotatable workpieceand substrate.

In use, clampis connected to the forward end of portable friction welding toolwith the end of colletextending therethrough to receive rotatable workpiece. With the workpiece secured in collet, clampA is brought to position the workpieceat the desired weld site. Leading edgeof clamp systempresents a gasketto secure the seal and vacuum provisionsof topside equipment(see) draw a vacuum through vacuum lineC to evacuate the area under clamp. Optionally, clampmay provide a subareadefined close about colletand provided with its own isolating leading edgeA and gasketA.

Depending upon the specifics of the application, purge provisionsmay be a useful option. The purge provisions can pipe supply air, exhaust air or a compressed gas into subarea. In this illustrative embodiment, purge provisionsuse a compressed gas tankA outfitted with purge line and controlsB. The ability to control the environment in the immediate area of an underwater weld site may be used to enhance the quality of the weld, e.g., control the quench rate (gas instead of residual water or salt water), allow for a dry weld and attendant properties, or allow the use of select inert gas when dealing with difficult materials (e.g., the use of argon or other inert gas to mitigate rapid oxidation when dealing with titanium) or to mitigate concerns with a potentially explosive environment. When deployed, purge provisionsare used to flood subareawith a gas while the surrounding area is under a vacuum.

Many alternative designs for clamping systems are possible, depending upon the application. One particularly advantageous system when an array of closely and precisely spaced fixtures is required is disclosed in provisional application 62/881,340 for Lau et al filed on Jul. 31, 2019 for A Mufti-position Clamp for Friction Welding Operations, the disclosure of which is hereby incorporated by reference.

After the weld has proceeded through the automated burn-off phase and upset phase, an appropriate cool down phase ensures full weld solidification and, in this embodiment, a manual reset triggers colletto release workpieceand withdraw. ClampA can be then be released, here by terminating the vacuum at vacuum clamp controlsand portable friction welding toolis withdrawn from substratein a straight out, perpendicular fashion. If the weld was conducted underwater, air supplyB from topside facilitiesshould not be shut off until portable friction welding toolhas been returned to the surface. Alternatively, components can allow for sufficient “blow-by” to ensure that there will always be a positive pressure differential necessary to prevent water from entering the tool.

An embodiment of the composition and operation of portable friction welding systemis illustrated through reference to the pneumatic circuit of, the flow diagrams of, and the pressure graph of.is one embodiment of a pneumatic circuit for the portable friction welding systemillustrated with the foregoing illustrative hardware and will be first described to address the composition of this illustrative circuit. In this embodiment these flow lines utilize intersecting pathwaysL (in the hardware figures) drilled (with unneeded portions plugged, backfilled with epoxy, tapped and capped or the like) in the body of the housing combined with channels and pathways defined within the interior of the housing to establish the circuitry. For the purposes of this illustration, the components of the portable friction welding system have been divided to topside equipment, operator controls, control module segment, supply valve pistonand welder segment. In this example, (topside equipmentcomprises a power source in the form of a compressorconnected to filtersto filter the air and to remove moisture in the line and regulatorA to establish an air supplyB. Optionally, air supplyB also drives vacuum clamp controlsas part of topside equipment. The vacuum clamp controls are connected to vacuum clampA at portable welding toolthrough a vacuum lineC.

Air supplyB of topside equipmentis connected to portable friction welding toolthrough air supply lineA. Air supply lineA is connected to control module segmentat supplied test port(denoted as accessand as an input to the vacuum module or V-90 control system modulethrough an inlet flow restrictionA and to flow control elementA associated with supply valve upper chamber check valve (“SVUCCV”). Flow control elementA combines an inlet flow restrictionA with a following chamberC of sufficient volume to effectively act as a timing circuit. SVUUC also has a fixed flow restrictionD a one-way check valveC and arranged to carry an alternate feed to the large side of a motor supply valve. Test port, designated, is positioned between vacuum moduleand flow controllerA.

As noted, the outflow of SVUCCVis connected to the large side of supply valve pistonwhich is also biased by a spring for nominal closure and provides test port, denoted as accessin. The small piston side of supply valve pistonis positioned between air supply lineA and air motorand therethrough on to exhaust lineB.

Returning to control module segment, the vacuum module, V-90 control of system modulehas an inlet restrictionA followed by a venturi effect producing fixed restrictionD followed by a fixed restrictionC. The normal outflow of vacuum moduleis connected to forging area controller (“FAC”)and therethrough to exhaust lineB. Test port, denoted access, is positioned between V-90 controls system module and FAC. The vacuum take-off lineB of V-90 control system moduleis connected to a second inlet to SVUUCVand, through BK check valve (“BKCV”), to the welder segmentatB the rear facing side of forging pistonA. As explained further below, vacuum take-off lineB is the conduit for positive pressure outflow from vacuum modulefor shutting off motorand presenting flow to BKCV. The BKCV has an inlet flow restrictionA, a fixed flow restrictionB and a one-way check valveC.

The rear facing side of the forging piston is also connected to test port(denoted as access) and to air supply lineA through forging pressure controller (“FPC”). FPCpresents an inlet restrictionA, an adjustable shut-off valveC and a one-way check valveD between the air supply and the forging piston.